1. Field of the Invention
The invention relates generally to the field of communications. More particularly, the invention relates to the detection of radio stations.
2. Discussion of the Related Art
Radio stations broadcast information encoded into radio-frequency (RF) signals on a plurality of transmission schemes. These RF signals may be, for example, amplitude modulated (AM) signals or frequency modulated (FM) signals. Typically, the transmitted information is decoded into an audio signal at a radio receiver.
Modern radio receivers include seek and scan functions. These functions are initiated by a user and attempt to search for a station that meets certain criteria. A seek function searches through radio channels and stops when the receiver finds the next station. A scan function also searches though radio channels and stops at the next station, but only for a limited period of time, repeating the process until terminated by the user.
Usually, in order for seek and scan functions to find and stop at radio stations, the quality of the received RF signal is measured. A typical technique includes determining if the signal strength is greater than a predetermined magnitude. Another metric used for signal quality measurement is ultrasonic noise (USN). A problem with these metrics is that they do not satisfactorily meet the requirements for finding suitable radio stations. Moreover, even when a good quality signal is found, the encoded information may be other than an audio signal (false alarm).
Thus, there is a need for a method and/or apparatus for utilizing metrics that can satisfactorily characterize the quality of received RF signals. Further, there is a need for minimizing false alarm rates.